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Illumination, noise and their impact on working conditions and on the human body. Occupational Safety and Health

Occupational Safety and Health / Legislative basis for labor protection

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Illumination

The greatest amount of information about the world around us gives a visual analyzer. For this reason, rational natural and artificial lighting in residential premises and public buildings, at workplaces is of great importance for ensuring normal life and human performance. Light not only ensures the normal functioning of the human body, but also determines the vitality and rhythm. Insufficient lighting of the workplace makes it difficult to work for a long time, causes increased fatigue and contributes to the development of myopia. Too low light levels cause apathy and drowsiness, and in some cases contribute to the development of feelings of anxiety. A long stay in conditions of insufficient lighting is accompanied by a decrease in the intensity of metabolism in the body and a weakening of its reactivity. Long-term exposure to a light environment with a limited spectral composition of light and a monotonous lighting regime leads to the same consequences.

Excessively bright light blinds, reduces visual functions, leads to overexcitation of the nervous system, reduces performance, disrupts the mechanism of twilight vision. Exposure to excessive brightness can cause photoburns to the eyes and skin, keratitis, cataracts, and other disorders.

Lighting that meets technical and sanitary and hygienic standards is called rational. The creation of such lighting in production, and especially in educational institutions, is one of the most important tasks of labor protection.

Light flow - the power of radiant energy, estimated by light sensation. The unit of measure is lumen (lm).

Illuminance (E) is defined as the luminous flux per unit area of ​​the illuminated surface. The unit of measurement is lux (lux), 1 lux is the illumination of a surface of 1 m2, to which a luminous flux of 1 lm is supplied:

E \uXNUMXd F / S,

where Ф - luminous flux, lm; S is the surface area on which the luminous flux falls, m2.

According to the type of light source, industrial lighting can be natural - due to solar radiation (direct and diffusely scattered light of the sky dome) and artificial - due to artificial light sources and mixed.

Daylight, created by natural light sources, has a high biological and hygienic value and has a strong impact on the human psyche. The illumination of rooms with natural light depends on the light climate of the area, the orientation of windows, the quality and content of window panes, the color of the walls, the depth of the room, the size of the light surface of windows, as well as objects blocking the light, etc. Natural lighting of rooms is carried out through light openings and can be made in the form of a side, top or combined (top and side). Lateral lighting occurs through windows in the outer walls, the upper one - through skylights located in the ceilings, combined - through windows and skylights. The natural illumination inside the premises is estimated by the coefficient of natural light (KEO).

KEO is defined as the ratio of natural illumination, created at some point of a given plane indoors by sky light (direct or after reflections), to the simultaneous value of outdoor horizontal illumination, created by the light of a completely open sky, expressed as a percentage:

e = (U/EN) 100%,

where EB - indoor illumination, lx; EH - simultaneous illumination by scattered light from the outside, lx.

The normalized value of KEO depends on the nature of the visual work, the type of lighting (natural or combined) and the light climatic zone. The norms established eight categories of visual work - from work of the highest accuracy (I category) to work with general supervision of the production process (VIII category). The choice of the KEO of the first seven digits is based on the size of the object of distinction. Illumination of the room with natural light is characterized by the KEO of a number of points located at the intersection of the vertical plane of the characteristic section of the room and the horizontal plane at a height of 1 m above the floor level. The minimum value of KEO, depending on the work performed, with top and combined lighting should be from 10 to 2%, and with side lighting 3,5-0,5%; at the point of the room furthest from the windows on the working surface of the table (desk), it must be at least 1,5%.

The best type of natural lighting for classrooms is lateral left-sided with the use of sun protection devices. With a depth of classrooms of more than 6 m, a right-sided illumination device is required. To create good illumination, it is necessary to clean window panes at least 4 times a year from the outside and at least 1-2 times a month from the inside. Windows and other light openings must not be blocked with various objects.

With insufficient natural light suit artificial lighting. Artificial lighting helps to avoid many of the disadvantages of natural lighting and to provide optimal light conditions. However, the conditions of occupational health require the maximum use of natural light, since sunlight has a healing effect on the human body.

In case of insufficient natural light during daylight hours, artificial light is also used. Such lighting is called mixed.

Artificial lighting according to the design is of two types: general and combined when added to general lighting local, created by lamps concentrating the luminous flux directly at the workplace. General lighting can be working, emergency and security.

Work lighting it can be general to provide illumination of the entire educational room and local, used in case of insufficient general lighting of desks, tables in reading rooms, etc. Artificial lighting is standardized in the range from 5 to 5000 lux, depending on the conditions and type of work performed. An important hygienic requirement is to protect the eyes from the blinding effect of light, which is achieved by using appropriate lighting fixtures and rationing the height of the suspension and the brightness of the luminaires. The smallest suspension height for lamps with a power of more than 200 W is 3 m from the floor level.

Emergency lighting provided in case of sudden shutdown of working lighting.

security lighting designed to limit dangerous areas. It should provide illumination at ground level of 0,5-1 lux.

The use of open lamps is dangerous, so they are used with additional fittings (diffusers, dimmers, lampshades, etc.), which protect a person's eyes from excessive brightness of the light source, forming a protective angle. Electric lamps together with fittings are commonly referred to as light fixtures. The choice of light sources is determined by their electrical, light, color characteristics, the size and shape of the flasks, and efficiency.

To ensure calculations for illumination in accordance with the SanPiN "Sanitary rules for the maintenance of general education schools and boarding school classrooms" and "Natural lighting and artificial lighting", industry standards have been drawn up, which are the values ​​of illumination for the main premises and workplaces of educational institutions.

In classrooms, desks and tables are placed so that the light falls on the left side of the students; the hanging height of the lamps must be at least 2,5 m. The workplaces in the workshops are arranged in such a way that the light fell on the left if possible, the workbenches were located perpendicular to the windows. Commonly used fluorescent lamps or lamps with incandescent lamps must be kept clean, they should be cleaned at least once every 1 months.

To increase illumination due to reflected light, walls, ceilings, floors are painted in light colors: ceilings are white, the upper parts of the walls are gray, blue, the lower ones are brown, gray, blue, dark green. Properly selected colors have a positive effect on the human psyche, reduce visual and general fatigue.

Illumination rating in premises and at workplaces is carried out by direct and indirect methods. Direct method is to determine the illumination using luxmeter, which is a microammeter connected to a photocell (usually selenium) and calibrated in units of illumination. indirect method illumination assessment is to determine the KEO. The results are then compared with standards.

Noise

One of the harmful production factors is noise - a random combination of sounds of different frequencies and intensities (strengths) arising from mechanical vibrations in solid, liquid and gaseous media. Noise adversely affects the human body, primarily on its central nervous and cardiovascular systems. Prolonged exposure to noise reduces the acuity of hearing and vision, increases blood pressure, tires the central nervous system, as a result of which attention is weakened, the number of errors in the actions of the worker increases, and labor productivity decreases. Noise exposure leads to occupational diseases and can also cause accidents.

Sources of industrial noise are machines, equipment and tools.

Human hearing organs perceive sound waves with a frequency of 16 to 20 Hz. Oscillations with a frequency below 000 Hz (infrasound) and above 20 Hz (ultrasound) do not cause auditory sensations, but have a biological effect on the body.

When sound vibrations of the particles of the medium, a variable pressure arises in it, which is called sound pressure P.

The propagation of sound waves is accompanied by energy transfer, the magnitude of which is determined by the sound intensity I. The minimum sound pressure P and the minimum sound intensity I, distinguished by the human ear, are called threshold. The intensity of barely audible sounds (hearing threshold) and the intensity of sounds that cause pain (pain threshold) differ from each other by more than a million times. Therefore, to assess the noise, it is convenient to measure not the absolute values ​​of the intensity and sound pressure, but their relative levels in logarithmic units, taken in relation to the threshold values ​​P and I

The decibel (dB) is taken as the unit for measuring sound pressure levels and sound intensity. The range of sounds perceived by the human ear is from 0 to 140 dB.

Sound vibrations of different frequencies at the same sound pressure levels affect the human hearing organs in different ways. The effect of sounds of higher frequencies is most favorable.

By frequency, noise is divided into low-frequency (maximum sound pressure in the frequency range below 400 Hz), medium-frequency (400-1000 Hz) and high-frequency (over 1000 Hz).

To determine the frequency response of noise, the audio frequency range is divided into octave frequency bands, where the upper cut-off frequency is equal to twice the lower frequency.

According to the nature of the spectrum, noise is divided into broadband with a continuous spectrum more than one octave wide and tonal, in the spectrum of which there are pronounced discrete tones.

According to temporal characteristics, noise is divided into constant and non-permanent (fluctuating in time, intermittent, impulse).

Noise is considered constant, the level of which changes over time by no more than 5 dB during an eight-hour working day, and non-constant - more than 5 dB. GOST 12.1.003-83 establishes the maximum permissible conditions for constant noise in the workplace, under which noise, acting on a worker during an eight-hour working day, does not harm health. Normalization is carried out in octave frequency bands with geometric mean frequencies of 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz.

Various types of noise measuring equipment are used to measure noise levels at workplaces in octave frequency bands and the overall noise level. The most widespread sound level meters, consisting of a microphone that perceives sound energy and converts it into electrical signals, an amplifier, correction filters, a detector and a dial indicator with a scale graduated in decibels.

Industrial noise disrupts information communications, which causes a decrease not only in efficiency, but also in the safety of human activity, since a high noise level makes it difficult to hear a warning signal of danger. In addition, noise causes ordinary fatigue. Under the action of noise, the ability to concentrate attention, the accuracy of performing work related to the reception and analysis of information, and labor productivity are reduced. With constant exposure to noise, workers complain of insomnia, impaired vision, taste sensations, digestive disorders, etc. They have an increased tendency to neuroses. The energy consumption of the body when performing work in noise conditions is greater, i.e., the work turns out to be more difficult. Noise can cause three possible outcomes by adversely affecting a person's hearing: temporarily (from a minute to several months) desensitization to sounds of certain frequencies, causing hearing damage or instant deafness. A sound level of 130 dB causes pain, and 150 dB leads to hearing damage at any frequency.

The maximum permissible levels (MPL) of noise exposure per person guarantee that after 50 years of work, the residual hearing loss for 90% of workers will be less than 20 dB, i.e. below the limit when it begins to interfere with a person in everyday life. A hearing loss of 10 dB is virtually unnoticeable.

Limit noise levels when exposed for 20 minutes:

by infrasound It is customary to call oscillations with a frequency below 20 Hz propagating in the air. The low frequency of infrasonic oscillations determines a number of features of its propagation in the environment. Due to the large wavelength, infrasonic vibrations are less absorbed in the atmosphere and more easily go around obstacles than vibrations with a higher frequency. This explains the ability of infrasound to propagate over considerable distances with little loss of partial energy. That is why conventional noise control measures are ineffective in this case. Under the influence of infrasound, vibration of large objects of building structures occurs, due to resonance effects and excitation of secondary induced noise in the sound range, infrasound amplification occurs in individual rooms. The sources of infrasound can be means of land, air and water transport, pressure pulsation in gas-air mixtures (large-diameter nozzles), etc.

Compressors are the most characteristic and widespread source of low-acoustic oscillations. It is noted that the noise of compressor shops is low-frequency with a predominance of infrasound, and in the cabins of operators, infrasound becomes more pronounced due to the attenuation of higher-frequency noises. Powerful ventilation systems and air conditioning systems are also sources of infrasonic vibrations. Maximum sound pressure levels reach 106 dB at 20 Hz, 98 dB at 4 Hz and 85 dB at 2 and 8 Hz.

In car interiors, the highest sound pressure levels are in the range of 2-16 Hz, reaching 100 dB or more. Moreover, if the car is moving with the windows open, the level can increase significantly, reaching 113-120 dB in octave bands below 20 Hz. The open window plays the role of the so-called Helmholtz resonator.

High infrasonic levels occur in bus noise, amounting to 107-113 dB at frequencies of 16-31,5 Hz with a total noise level of 74 dB. The noise of some self-propelled machines, for example, a bulldozer, has an infrasonic character, in the noise of which the maximum energy at frequencies of 16-31,5 Hz is 106 dB.

Jet engines of aircraft and rockets are also sources of infrasound. During takeoff of turbojet aircraft, infrasound levels gradually increase from 70-80 dB to 87-90 dB at a frequency of 20 Hz. At the same time, another maximum is observed at frequencies of 125-150 Hz, so this noise still cannot be called pronounced infrasound.

From the above examples, it can be seen that infrasound at workplaces can reach 120 dB or more. At the same time, workers are more often exposed to infrasound at levels of 90-100 dB.

In the sound range of 1-30 Hz, the perception threshold of infrasonic vibrations for the auditory analyzer is 80-120 dB, and the pain threshold is 130-140 dB.

Studies conducted in production conditions indicate that in the case of pronounced infrasound of relatively low levels, for example, 95 and 100 dB with a total noise level of 60 dB, complaints of irritability, headache, absent-mindedness, drowsiness, dizziness are noted. At the same time, in the presence of intense broadband noise, even with sufficiently high levels of infrasound, these symptoms do not appear. This fact is most likely related to the masking of infrasound by noise in the audio range.

ultrasound it is customary to consider oscillations with a frequency above 20 kHz, propagating both in air and in solid media, i.e., ultrasound contacts a person through air and directly from a vibrating surface (instrument, apparatus and other possible sources).

Ultrasonic equipment and technology is widely used in various sectors of the national economy for the purpose of active influence on substances (soldering, welding, tinning, machining and degreasing of parts, etc.), structural analysis and control of the physical and mechanical properties of substances and materials (defectoscopy ), for processing and transmitting signals in radar and computer technology, in medicine - for diagnosing and treating various diseases using sound imaging, cutting and joining biological tissues, sterilizing instruments, hands, etc.

The ultrasonic frequency range is conditionally divided into low-frequency - from 1,12-104 to 1,0-105 Hz and high-frequency - from 1,0-105 to 1,0-109 Hz (GOST 12.1.001-89). Ultrasonic devices with operating frequencies of 20-30 kHz are widely used in industry. The most common sonic and ultrasonic pressure levels in industrial workplaces are 90-120 dB. The thresholds for auditory perception of high-frequency sounds and ultrasounds are 20 dB at a frequency of 110 kHz, up to 30 dB at 115 kHz, and up to 40 dB at 130 kHz. Considering that low-frequency ultrasounds (up to 50 kHz) are much more than high-frequency noises, they attenuate in air as they move away from the source of vibrations, we can assume their relative harmlessness to humans, especially since extremely insignificant absorption occurs at the interface between the "skin and air" media. incident energy (about 0,1%). At the same time, a number of studies indicate the possibility of adverse effects of ultrasound through the air.

The earliest adverse subjective sensations were observed in workers servicing ultrasonic units - headaches, fatigue, insomnia, exacerbation of smell and taste, which later (after 2 years) were replaced by inhibition of the listed functions. Workers servicing ultrasonic industrial installations have been found to have disturbances in the vestibular analyzer. Ultrasound can affect workers through the fibers of the auditory nerve, which conduct high-frequency vibrations, and specifically affect the higher parts of the analyzer, as well as the vestibular apparatus, which is closely related to the auditory organ. Studies by domestic scientists to assess the effect of airborne ultrasounds on animals and humans have made it possible to develop standards that limit sound pressure levels in the high-frequency region of sounds and ultrasounds in 1/3-octave frequency bands.

Permissible levels of high-frequency sounds and ultrasounds:

High-frequency ultrasound practically does not propagate in the air and can affect workers only when the source of ultrasound comes into contact with the surface of the body.

Low-frequency ultrasound, on the contrary, has a general effect on workers through the air and a local one due to the contact of hands with the workpieces in which ultrasonic vibrations are excited. The effects caused by ultrasound can be conditionally divided into mechanical - tissue micromassage, physico-chemical - acceleration of diffusion processes through biological membranes and a change in the rate of biological reactions, thermal, as well as effects associated with the occurrence of ultrasonic cavitation in tissues (under the influence of only powerful ultrasound) . All this indicates a high biological activity of this physical factor.

The working conditions of workers in various processes using high-frequency ultrasound are very diverse. For example, the work of operators of ultrasonic flaw detection is accompanied by psycho-emotional stress and fatigue of the visual analyzer associated with the need to decipher signals, overstrain of the musculoskeletal system, especially the hands, which is due to the forced posture and the nature of the movements made by the hand associated with the movement of the finder along the controlled surface.

In production conditions, ultrasound propagating by contact can be combined with a complex of unfavorable environmental factors: unsatisfactory microclimatic conditions, dust and gas content in the air, high noise levels, etc. As a result of significant absorption in tissues, adverse effects that develop under the action of ultrasound during contact transmission, usually expressed in the contact zone. Most often, these are fingers, hands, although distal manifestations are also possible due to reflex and neurohumoral connections.

Prolonged work with intense ultrasound during its contact transmission to the hands can cause damage to the peripheral nervous and vascular apparatus (vegetative polyneuritis, paresis of the fingers). At the same time, the degree of severity of changes depends on the time of contact with ultrasound and may increase under the influence of unfavorable concomitant factors of the production environment.

The normalized parameters of ultrasound propagating by contact are the peak value of the vibration velocity (m/s) in the frequency band 8-31,5-103 kHz or its logarithmic level in decibels (dB).

To combat noise in the premises, measures of both technical and medical nature are carried out:

• eliminating the cause of noise or significantly reducing it at the source itself during the development of technological processes and equipment design;
• isolation of the noise source from the environment by means of sound and vibration protection, sound and vibration absorption;
• reduction in the density of sound energy of rooms reflected from walls and ceilings;
• rational layout of premises;
• use of personal protective equipment against noise;
• rationalization of the working regime in noisy conditions;
• medical preventive measures.

The most effective way to deal with noise caused by vibration from shock, friction, mechanical stress, etc. is to improve the design of equipment (changing technology to eliminate shock). The reduction of noise and vibration is achieved by replacing the reciprocating motion in the nodes of the working mechanisms with a uniform rotational one.

If it is not possible to effectively reduce noise by creating a perfect design of a particular machine, it should be localized at the place of occurrence by using sound-absorbing and sound-insulating structures and materials. Airborne noise is attenuated by installing special enclosures on machines or placing noise-generating equipment in rooms with massive walls without slots and holes. To exclude resonance phenomena, the casings should be lined with materials with high internal friction.

To reduce structural noise propagated in solid media, sound and vibration isolation floors are used. Noise reduction is achieved by using elastic pads under the floor without their rigid connection with the supporting structures of buildings, by installing vibrating equipment on shock absorbers or special isolated foundations. Vibrations propagating through communications (pipelines, channels) are weakened by joining the latter through sound-absorbing materials (rubber and plastic gaskets). Along with sound insulation in production conditions, sound absorption means are widely used. For displacements of small volume (400-500 m3), general wall and ceiling cladding is recommended, which reduces the noise level by 7-8 dB.

Noise reduction can be achieved through rational building planning: the most noisy rooms should be concentrated in the depths of the territory in one place. They should be removed from the premises for mental work and fenced off with a green area that partially absorbs noise.

In addition to technological and technical measures, personal protective equipment is widely used - antiphons, performed in the form of headphones or earbuds. There are several dozen options for in-ear plugs, headphones and helmets designed to isolate the ear canal from noise of various spectral composition.

The negative effect of noise can be reduced by reducing the time of their exposure, organizing a rational work and rest regime, providing for short breaks during the working day to restore hearing function in quiet rooms.

Limit noise levels:

Authors: Volkhin S.N., Petrova S.P., Petrov V.P.

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